1. Field of the Invention
The present invention relates generally to engine repair kits and tools, and more particularly to a bushing replacement kit for removing and replacing the accessory drive bushing in the front gear cover of certain diesel engines that permits removal and replacement without removing the gear cover from the engine, and that may be adapted for use with other structures having bushing inserts.
2. Description of the Related Art
Innumerable internal combustion engines and other mechanisms are provided with various rotary input and output shafts for drive shafts, accessory drives, etc. These shafts often pass through a passage in the primary or accessory case or housing of the engine or mechanism. Such drive passages are generally provided with a bearing or bushing of some sort in order to avoid wear and tear upon the walls of the passage and/or the rotary shaft passing through the passage, and to provide proper lubrication to the shaft and passage interface.
An example of such a structure is found in the accessory drive and front gear cover of the Cummins N-14 Plus diesel engine. This engine includes a front gear cover that protects the various drive gears from contamination from dirt, etc., and confines lubrication within the gear case defined by the front of the engine and the front cover. An accessory drive passage extends through the cover, through which an accessory drive passes to drive various rearwardly disposed components (e.g., the air compressor, the fuel pump, etc.) from a forwardly disposed belt driving a pulley on the front end of the accessory drive shaft. The accessory drive passage includes a sleeve bearing or bushing therethrough, which protects the softer cast aluminum cover material and provides a smooth surface within which the accessory drive shaft may rotate.
Mechanics familiar with this type of engine recognize this area as a weak point, since the asymmetric belt loadings on the drive pulley of the accessory shaft tend to wear the bushing out of round, particularly if the drive belt tension is too tight. This can allow excessive oil past the accessory drive shaft to the front seal, with the excessive oil pressure leading to premature seal failure and oil leakage. Such leakage is a likely sign of excessive bushing wear and failure.
The bushing may also spin within its passage through the front gear cover if frictional forces between the rotary shaft and the bushing are sufficiently high and/or the bushing loosens within its passage through the front gear cover. When this occurs, it can cause damage to the accessory drive shaft in short order due to the misalignment of the radial oil passages through the bushing wall and front gear cover passage and subsequent starvation of lubricating oil to the shaft. A spun bushing will also damage the interior wall of the accessory drive passage of the gear cover, often tearing out sufficient material that a new standard bushing cannot be reinstalled.
When such a situation occurs, i.e., the front gear cover has been damaged due to a spun bushing or other cause that precludes the replacement of the old bushing with a new standard bushing, conventional procedure has been to remove the old front gear cover and replace it with a new cover. This is a very costly procedure, as the front gear cover for a Cummins N-14-engine costs over two thousand dollars as of mid-2007. The labor required to remove and replace the cover adds further to this replacement cost. Even in those cases where the bushing may be replaced, conventional practice is to remove the front gear cover from the engine for installation of a new bushing using a mallet or arbor press or the like. The time consuming and costly labor required for the removal and reinstallation of the front cover, has been noted above.
Thus, a bushing replacement kit solving the aforementioned problems is desired.